/**
 * Copyright 2005 The Apache Software Foundation
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.mapred;

import java.io.IOException;
import java.io.File;
import java.util.Arrays;

import org.apache.hadoop.fs.FileSystem;

import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.conf.Configuration;

/**
 * An {@link OutputFormat} that writes {@link SequenceFile}s.
 */
public class SequenceFileOutputFormat extends OutputFormatBase {

    @Override
    public RecordWriter getRecordWriter(FileSystem fs, JobConf job,
                                        String name) throws IOException {

        File file = new File(job.getOutputDir(), name);

        final SequenceFile.Writer out = new SequenceFile.Writer(
                fs,
                file.toString(),
                job.getOutputKeyClass(),
                job.getOutputValueClass(),
                job.getBoolean("mapred.output.compress", false));

        return new RecordWriter() {

            @Override
            public void write(WritableComparable key, Writable value)
                    throws IOException {

                out.append(key, value);
            }

            @Override
            public void close(Reporter reporter) throws IOException {
                out.close();
            }
        };
    }

    /**
     * Open the output generated by this format.
     */
    public static SequenceFile.Reader[] getReaders(Configuration conf, File dir)
            throws IOException {
        FileSystem fs = FileSystem.get(conf);
        File[] names = fs.listFiles(dir);

        // sort names, so that hash partitioning works
        Arrays.sort(names);

        SequenceFile.Reader[] parts = new SequenceFile.Reader[names.length];
        for (int i = 0; i < names.length; i++) {
            parts[i] = new SequenceFile.Reader(fs, names[i].toString(), conf);
        }
        return parts;
    }
}

